| Amnesty claims it found these UK-made cluster bombs in Yemen |
Since 2010 it has been illegal under British law to supply the bombs, which put civilians at risk by releasing small bomblets over a wide area.
Labour said it was "deeply worrying" cluster bomb use had been confirmed. The UK is supporting the Saudi-led coalition which is fighting the Houthi rebel movement in Yemen.
In a statement to MPs, Mr Fallon said the UK had not supplied any cluster bombs to Saudi Arabia since 1989.
But he added that Saudi investigations had concluded that some UK-made cluster bombs had been dropped.
The BL-755 bombs will no longer be used by the coalition, he added.
Cluster bombs explained
- The Convention on Cluster Munitions prohibits all use, stockpiling, production and transfer of cluster bombs
- The convention has 108 signatories and became binding international law in 2010
- Cluster bombs pose particular risks to civilians because they release many small bomblets over a wide area
- During attacks, they are prone to indiscriminate effects especially in populated areas
- Unexploded bomblets can kill or maim civilians long after a conflict has ended, and are costly to locate and remove